Horses and other animals are sometimes located in environments having airborne particulate matter, such as stables, training areas, or race tracks. The airways of horses or other animals may be irritated or inflamed, or the breathing function impeded, by the inhalation of particulate matter, such as dust, dirt, pollens, grains, grasses, or hay particles. Inhalation of these materials, particularly hay and some processed grains, may lead to allergic reactions or the respiratory condition known as “heaves,” which is also known as recurrent airway obstruction. Believed to be primarily caused by chronic exposure to dusts and molds in hay and other materials, heaves can greatly impair the function of a horse's lungs, making it difficult for the horse to breathe at rest, and even more so during physical exertion. Similar to human asthma, heaves may cause the muscles inside the airways to constrict in response to external stimuli such as dust, pollen, or mold.
Horses typically breathe primarily through the nose. When feeding on hay, grains, oats or other dry materials, a horse may be susceptible to inhaling the feed or other particulate matter into the nostril, particularly if the horse inhales air through its nose while its nose is positioned near the feed. The feed may also tend to collect on the horse's nose during feeding, particularly on any moist regions of the nose. Moreover, particles such as dust, dirt or dander may be released into the air while a horse is being cleaned.
Various types of masks have been developed for use with horses to perform various functions. Fly masks have been designed to protect the sensitive areas of a horse's head from flies or gnats. Pre-warmer masks have been developed for cold-weather horse racing to warm the air entering a horse's nasal cavity and lungs. Other masks for use with horses have been designed to administer medication, such as bronchodilators or Corticosteroids, by inhalation.
Previous masks, however, do not filter air entering the nostrils, or cover the nose and mouth, and thus are not useful during feeding, when the susceptibility to inhaling hay and grain particles may be heightened.